1. Field of the Invention
The invention relates to combustion turbine power plants and more particularly to fuel heating systems for combustion turbine power plants.
2. Background Information
It is known in the art to provide steam to preheat combustion fuel oil to vaporize the oil for use in combustion turbine systems. Typically an intermediate fluid, such as water, is heated until it becomes a gas, then the steam is mixed with the fuel oil, thereby heating and atomizing the fuel oil. The fuel heating steam may be provided by a separate steam boiler. Such a boiler adds a significant cost to the power plant. Alternatively, it is known in the art to indirectly utilize the exhaust gas from the combustion turbine to heat the steam. This type of system can be more costly due to the additional heat exchanger.
One prior art approach disclosed in U.S. Pat. No. 4,932,204 recovers heat available in the exhaust gas of the combustion turbine by increasing the water flow through the economizer section to a rate in excess of that required to match the steam production rate in the evaporator section. The excess water flow is withdrawn from the heat recovery steam generator at a temperature approaching the evaporator temperature and used to preheat the fuel delivered to the combust of the combustion turbine.
Another approach proposed to preheat fuel oil is to use waste heat from the combustion turbine rotor air cooler to raise the fuel temperature to above 600.degree. F. (315.degree. C.) One draw back to using the rotor air cooler waste energy is that it requires a complex arrangement and sophisticated controls to maintain relatively constant fuel temperature while simultaneously maintaining the required cooling for the rotor over the possible range of operating loads for the turbine.
Therefore, what is needed is a combustion turbine fuel oil heating system that is simple, economical, will allow the fuel oil to be heated above 600.degree. F., if desired, and can be used in a simple or combined cycle combustion turbine power plant.